Armor piercing projectile



NOM/19,1935. QFQNACl y 2,021,685 K l' y ARMOR PIERCING PROJEC'IILE Nam i9, E935. c. FoRNAcl n ARMOR PIERCING PROJE 4L 4# v77 75 i I 3 l C". .Fornaci Ef n v NOV. 19, 1935. C, F0RNA| 2,021,685L

I f ARMORPIERCINGPROJECTILEL y l Filed June 2o, 195s V 4 'sunsets-sheet 4 Patented New.k 19,- i935 4STATES l 2,oz1,es5 ARMOR rmncmo rnoxaoms vcum Fornaci, 'rei-ni, muy.

Application June zo, 1933, serial No. 676,737 V 1n muy July 11, 1932 1o claims. (ci. 1oz-z8) `the base of the projectile of some sections of minor resistance, in. correspondence of the grooves for the driving bands and of the threaded mortise of the screw plug; whenever the breakage takes place the charge is rendered impossible of explosion and the destructive e'ect of the projectile irremediably compromised.

Various means have heretofore been proposed for avoiding this serious disadvantage. None of the known means have however proved entirely satisfactory and reliable at all times and under various conditions of attack of a hard facedarmor plate.

Furthermore it is clear that even if the breakage does not take place the deformations suffered by the projectile always imply a certain quantity of energy absorbed andnot utilized for the effects of perforation; it is consequently necessary to reduce said loss to a minimum in order to increase the efiiciency of the projectile.

Object of the present invention is to propose a piercing projectile which in the unfavourable conditions of ring, as those above mentioned, is not subjected to those strains producing deformations and breakage of the base While at thesame time with respect to projectilesv of common 'type a better utilization of the impact energy is realized for the eiects of the perforation of the armor plate.

40 'I'he construction is based on the fact, generally known, that deformations and breakage of the base or body preferably occur when the hole pro- Y duced in the armor plate has a very narrow and remarkably circular section, while there are very rare examples of the inconvenience occurring when the hole is of remarkable dimensions with regard to the projectile, but all these cases vmay be explained. through Vthe' intervention of accidental factors. Without entering into a detailed analysis of all the phenomena occuring during perforation it may be easily deduced from above considerations that the strains producing the breakage of the base or body of the projectile cannot have any way of manifestation if there is the possibility for the` projectiles body to be easily freed from the holeproduced on the plate. Meanwhile in order to avoid angular displacements or oscillations of the projectile which may cause its base f to be blocked and drawn out through' the hole, V5 and in any casein order'torendenzvoid the eiect of said displacements and oscillations it is necessary that Athe projectiles body may be shaped-in such a way that it cannot be gripped at all and blocked by the edges of the hole. K 10 To that'g'object the projectiles body instead of being of the usual cylindrical shape with a diameter only a little smaller than thatof the fore ring or front bandthat is approximating 1%, is

i provided for with a remarkably tapering shape 15 from the ogival,l head or fore ring downwards to the base. This `Ytapering form may be usually Y conical, that is composed of one or more trun-r cated conlcal surfaces eventually combined with one or more cylindric surfaces, all concentric'o with the axis of the projectile and` conveniently jointed together and to the remaining partsrof the projectile; according to circumstances rcurvilinear or mixed profiles may be also provided for, that is profiles consisting of curvilinear and z5 rectilineal sections with different inclinations to the axis of the projectile.

Generally speaking the nature of the profile of the tapering part of the projectiles bodyhas to beV determined for each case in particular in re 3o lation with the shaping of the explosion chami ber, the thickness of the projectiles parts and the results of trials executed.

The essential is that there should be a remarkable difference of diameter between the fore'part 35 of the projectile which denes the dimensionsY offithe hole kon the armor plate and its base.

lWhen these conditions are realized it is evident that the playbetweenthe edges of the hole and the body of the projectile gradually increasesjas 40- the .fprojectile proceeds through the thickness of Y the armor plate, the danger for the body or base being blocked and broken being meanwhile entirely removed with the further advantage not to be neglected of a smaller quantity of energy 45 being wasted owing to-friction and deformation of the projectile.

Of course within the limits of protection of the invention there are alsovcomprised all Vthose, proles in which the tapering begins in anypoint 50 whatever of the cylindric projectilessbodyand consequently after the fore ring; provided in each case this original point is before the driving band. In fact whenever it only matters to maintain the projectiles body integral. "(and it is possible to 55 l neglect the greater absorption of energy occurring during the perforation with respect to com- Y pletely tapered projectiles) itris'clear that it will do to give a slippery shape only to the partofV f the projectile directly subjected tobe blocked in the hole produced on the armor plate. .In con-V sequence the projectiles body is maintained from the fore ring downwards for a certainlength of the usual cylindrical form with a. diameterY only a little smaller than that of the said fore ring' and then inthe point recognized as convenient assumes one of the tapering profiles above men I tionecl. In any case it is however necessary that the tapering should beginbefore the driving bands to avoid to provide grooves for the application of said bands always constituting a zone of smaller resistance and may be. gripped' by the edges of the hole the effect of the slippery shape being thus destroyed. 2o As to the entity of the tapering it is to remark at according to practical trials it is advisable :lo :ixa difference of diameter of at least 10 to 2 between the fore part of the projectile Vdeg the dimensions of the hole on* the armor e and the bottom end; of courseif owing to nar exigencias asmaller Adifference may be pictured then the percentage indicated will be provided always over 1%, in said cases the.

objects of theinvention being equally obtained.

the driving bands which in their present in moet necessarily be applied on a diameter not be inserted with the usual methods on the ojectiles body. Y

Moreover as already mentioned it is necessary remove from thebodyof the shell and especially from its base vall parts or lines of reduced strength as driving band grooves; it isthen necesto sary to Ydiscover means for overcoming this oulty.

jacket partially or totally enveloping the tapered portion oi' the shell with the object'of providing i5 ef necessary support for the drivingr bands, which as a matter of fact may be also integral with the jacket. j

. sale jacket may Vbeamten to the body of theV shell by a cylindrical or conical threading, by

50 soldering the contacting surfacesV by a. process similar to the one used for the caps;` or also by heating or by contraction in which case the profile Lirical section of a sufficient length. Y 55 Should the jacket consist of al sumciently plastic materialV it may be conveniently applied Vby a similar .manner as the' driving bands, thatjis vby .means "of a hydraulic press or other like device oi the tapered portion has to comprise a cylin- Vby which it is tightened in the heat or cold against im* the outside surface of the shells body conveniently provided with projections capable of penetrating :into the jacket. y

Whatever may beV the system chosen for the application said jacket has to fulill the following.

o. the projectile;

consequence of the projectilers shape above little diierent from the bore .of the gun.

` In this aspect it is advisable that the jacket should VSuch a device generally comprises'av metallic by the riding of the gun may be transit must be tight-cisne connected with the ,f l.lers `body to ineke .it gas-tigl'it so that the ing itself fromthe projectiles body or by breaking 5 without an excessive strain or during the penetration through the armor plate or by the action of the repercussion at the impact' of the projectile on the plate, is to be negligible;

(e)` thejacket should allow, when necessary 10 the application of a device whatever capable of modifyingY the external profile of the-projectiles body for bringing said profile back to a correct ballistic shape.

. Y Numerous are the systems which may be de- 15 vised for realizing said organ simply called for brevitys sake jacket .which is to be studied for Veach singular casewlth the vcontribution of the results of lrings for trial executed with the object of choosing the most adapted type for each .but also for the object of protecting the base of the projectile against rupture, the direct contact between said base and the edges of the hole produced on the armor plate being thus avoided.

cover a'considerable'part of the body of the projectile. l

Only by Way -of example for the realizations of above fundamental ideas are now briefly described, as follows, modifications of a perforating 40 Y projectiles body according to the present invention. Y

:In the accompanying drawings: 1

Fig. l illustrates' a longitudinal section of a shell according to the rst modification.

Fig. 2 shows a longitudinal section of the shell accordingVV to a second modication.

Fig. 3 isalongtudinal section of the shell according toa third modication.

Fig. 4 isa longitudinal 'section of the shell ac- 50 cording to afourth modification. f

Fig. 5 is a longitudinal section of the fifth modication. v

Fig. 6 is a longitudinal Vsection of the sixth modification.V

With reference to Fig. 1 after the ogivalhead and from the fore ring (i) (these two parts being destined-to produce the efficient work of penetration) the prole of the projectiles body becomes conical,V this conical shape being maintained constant as far as near the bottom end. In correspondence to the median lineof the mortise for Vthe screw plug, that is in a zone where an excessive tapering off of the'projectiles walls cannot represent a danger, said conicity increases re- G5 markably, so that a, still more slippery shape is offered to the edges of the holev on the armor plate.

The screw plug destined to constitute a back closure for the explosion chamber and to bear the fuse is of the ordinary. type.

The gas .tight closure is secured byV a lead packing (Zlins'ertedbetween the baci: flange of the screw plug and an adapted annular seat provided on the back end of the projectiles Walls.

I aesinet Y fore edge (I4) of said ring solder or'other filling Vmaterial may be applied for better connecting The copper packing (Si) inserted between said lionne ci tno screw plug and the mctcllicjackct oi) servos cn the contrary not only to better se curo the close tightness produced by the screwV plug but also to prevent eventual inrlltratlons of the gases ci' the service charge between the jacket (d) and the projcctiles body.

The metallic jacket (fl) is enveloped round the.

to the compressive strains as those substantially'` produced in the gun, but at the same time relatively fragile as to easily break as soon as coming in contact with the armor plate.-

type of fine thread is such that not a great resistance may be opposed to the sliding oi of the jacket under the action of the edges of the hole on the armor plate acting against the fore edge 5) of the jacket.

Between the edge (5) ofthe jacket and the fore part oi the projectile a sheet casing is applied by means of tin solder, the casing being suciently thick toreslst to accidental shocks or falls of the projectile, Without increasing in a sensible way the resistance opposed to the penetration through the plate and allowing the external profile of the projectiles body to take again the usual cylindric shape by avoiding reentrancies or sharp edges which might be detrimental the projectlles motion on the trajectory. v

ccording to the second modification illustrati-'- ed in Fig. r3 the projectiles body has nearly the same profile es in Fig. 1 The metallic jacket (fl) is connected to the projectile by a fine' conical thread as according to the rst modication; however said jacket has the characteristic or completely enveloping the whole lbase of the projectile and being closed by the bottom'(8), bottom and jacket forming one piece so that the projectiles body is completely withdrawn from the direct action of the gases of the service charge. Consequently the screw plug (Q) has they dimene sions strictly necessary for lodging theV fuse and eiecting a closure of the projectile sufficient for the detonation of. the explosive contained therein, the capacity of the projectiles chamberbeing thus utilized in the best Way for the action of illustrated of a shells body ypartially tapered ac-Y the explosion charge. Y

The metallic packing (lll) inserted between` 'the iiange of theA screw plug and the annular seat provided on the end oi the projectiles walls and the metallic packing (il l) inserted between the basV base do not serve for tight closing but to uniformly distribute the tighteningpressure of the screw plugs thread and ci the jacket respectively.

.Between the fore edge (l2) of the jacket and the fore part of the projectiles body there is n Should however this breakage not occur in due time the themetallic jacket.

is) of the jacket and. the projectlles' the profile with the fore ring. A

According to the third modification shown in, Fig. 3 the projectlle's body becomes conical'i'rom the fore ring downwards, and this coniclty is constant for the whole length the minimum 'dlarn- I eter beingf'reached against the small stop (I5) provided on the same base ofthe projectile.

Object of said stop (I5) ls to produce with the 10 metallic jacket '(4) a tight closure so as to avoid I eventual inltrations of gases between thesaid jacket and the projectiles body, said stop being proportioned in -such e. way that it Ymay break without offering too much resistance to the jack-v, 1 et for sliding oi fromthe projectile's body dur- I ing the penetration through the armor plate. Y'

The jacket (a) is integrsiwith the driving bands. j and is obtained out of a metallic ringapplied by againstthe milled body Vr( I6) .and then turned on the spot. Between the Voriginal point (I) of, the Y tapering and the fore edge(II) of the metallic jacket there may be provided' tin solder or oth- -v a hydraulic press or other similar machine 20Y er similar filling material in order to remove the .25

small reent-rancy producedon the bodyfof the.- projectile during manufacture. i 1

All theremaining organs of the projectile are' of usual type; onlyV Vto be remarked is the trapef zoidal thread chosen for the screw plug with the object of improving Vthe connection with theY breech block.

Asilol the 4th modification shown in Fig. 4 there is no need of particular specifications, the modification differing very little from the third illustrated in Fig. 3, the tapering. off beginning just near the middle of the projectiles body rather than from the forering.

lilso Vfor ,the fth' modification illustrated in Fig. 5 a detailed descriptionis not necessary the diierence as regards the third modification.' illustrated in Fig. 3 being only that the shells body instead of being entirely conical is partially coni-l Y gradually tapered so as to be flushed with point? 5 of the shells` body. In correspondence of this' point 2 tin solder may be applied in order to conceal the slight projection of the fore rim of According to Fig. 6, a sixth modification is 5 cording to a multilineal' profile. Fro'mthe'origin` I of the tapering the shells body shrinks in the diameter at rst abruptly so that a small shoulder is produced for supporting the jacket; thenv c gradually continues according to Va curvilineal Vproiile'as Vlar as a diameter is' obtained of 13% vsmaller than the initial one, with said diameter the body continuing of a cylindrical shape down to the base end. The metallic jacket E is applied around this tapered portion, the external profile of the shell being thus brought back to the usual cylindrical shape, the jacket being united to the shellsbody by welding the contacting surfaces and olY a second ring corresponding to the cylin- 75 f or syncing nnss on the shenin heteondiuons. j 7o et, said driving band and metallic jacket beingv drical part, made solidary with the body by means above specied. Y

It is evident also that in proximity of the base the end and preferably in correspondence of the rearer range and a greater exactness of firing represents an indirect and not to be neglected advantage of this invention since the drivingrbands are no longer inserted inthe projectiles. body and can'be arranged in the position of greatest el-` Vciency ywithout any fear about the integrity oi' the projectiles bottom.

Having `Vnow particularly described and ascertained'the nature of my said invention and in" what manner the same-is to, be performed, I declare that what I claim is: Y

l. A projectile including a body, a driving band on said be ly, a screw plug in said body, said body having an ogival headof a diameter corresponding to the calibre and being progressively tapered in the direction of the base from a point in front of the driving band, the profile of said tapered portion being devoid of sharp diametrlcal reductiene of section in the zone adjacent the screw plug, a metallic jacket substantially enveloping the whole tapered portion of the body from the base thereof and supporting said drivingband, said jacket having an external shape to form a cylindrical continuationpf the projectilebody,

means to tightly t said jacket on said'body` against the passageof gases of the service charge and to transmit to the jacket the'rotation im-f parted by the'gun rifling and to permit the jacket 4 to be detached'from the projectile body only during the piercing of the armor plate, a minimum resistancerbeing thus oiered to the air by the jacket on the trajectory.

2. A projectile Vasclairned in claim l characterlzed in that said body'terminates at its rear end in a projecting rim of relatively small thickness liable to breakage during the piercing of the armor plato and retaining the metallic V Y Y f there is a circumferential rim at the rear-end of the body integral therewith and oi substantially Vless thickness, the rear-end of said jacket abutjacket.

`3. A projectile Yas claimed in claim 1 characterized in that said body terminates at its rear end in a projecting rim' of relatively small thickness liable to breakage during the piercing of the armor plat/e and retaining the metallic jackformed integral and cf the same material.

4. A projectile as claimed in claim 1 characterized in that said metallic jacket consists of a plurality of annular elements applied one behind the other about the tapered portion of said projectile. Y

5. A'projeqtile including an ogival head, a front band of the largest diameter allowed bythe n' calibre and a body progressively shrinking in diameter for at least the' greater portion of its length from the front band toward the base, a

jacket 4oi? relatively plastic material rigidly applied around said part shrunk in diameter. a driving band on said jacket, said jacket extending in front ofgsaid band with an external diameter smaller than the diameter of the shells head and decreasing in thickness progressively so as 1 to become flush with the external surface of the body. y

6. A projectile including an ogival head, affront band of the largest diameter allowed by the calibre and a body progressively decreasing in diameter from the front band towards the base, a jacket of relatively plastic material rigidly applied around said part of lesserzdiameter, a driving band on said jacket, said jacket extending in .A front oi' said` band with an external Ydiameter Vsmaller than the diameter of the shells head and decreasing in thickness progressively so as to become flush with the external surface of the body.

'7. A projectile including an ogival head,`a front bandof tbe largest diameter allowed by the calibre and a body having a cylindrical section at the forepart and .decreasing in diameter but free from abrupt decreases from a point between the front and the; driving band and a substantial distance in advance of the driving band, toward the base, a jacket of arelatively plastic material Arigidly applied around said part of decreased diameter, a. rivingband `carried by vsaid jacket, said jacket extending in front of said band with an external diameter smaller than the diameter of the shells head and decreasing in thickness progressively so as to become flush with the external'surface of the body.

8.V A projectile including an ogival head, a body a jacket of relatively plastic material rigidly applied around said body, a driving band carried by said jacket said body being of its maximum diameter at a point between the front of said body and said driving bandbut substantially in front Ygreater than the maximum diameter of said body.

9. A projectile asclaimed in claim 5, inwhich tingagainst said rim whereby the jacket is retained on the projectile during ight but may be torn away during perforation.

10. A projectile as claimed in claim 6, in which there is a circumferential rim at the rear-end of the body. integral therewith and of substantially less thickness, the rear-end of said jacket abut- Vting against said rimv whereby the jacket is retained on the projectile during flight but maybe torn away during perforation.

CURIO FORNACI.

' of said driving band and decreasing toward the 

